Personal communication system (PCS) products such as second generation cordless telephone (CT2) and digital European cordless telephone (DECT) are examples of radio communication protocols. Signal quality in a radio communication system is an important decision making factor in maintaining a good communication link between communication devices. Information on the integrity of the link can be used to mute (squelch) audio or indicate error probability.
In today's digital communication devices which carry digitized voice, it is important to realize the situations that can occur during a communication session. When a communication link has been established and two parties are at opposite ends of the communication link, a reliable communication path must be maintained. If the communication path fails, the units should be capable of muting the digitized voice, thus preventing the end users form hearing noise bursts from corrupted receive data. In current systems there are very few ways to obtain this function, and the ways that are present are very slow to respond, easily falsed, or not practical to implement into existing systems.
In addition, in digital communication systems using time division multiplexing, synchronization is required so that a communication unit receiving information "knows" at what times the information is to be received. Once synchronization is achieved, the communication signals received are subject to deterioration for a variety of reasons. Among these are loss of transmission at the other end of the communication link, interference on the same or adjacent channel, and fading of the received signal due to increasing distance between the transmitting and the receiving units. When a "bad" signal (or portion of a signal) is received the user of the receiving unit may hear annoying pops or bursts, or possibly even lose the communication link. Thus, a need exists for an improved communication device that overcomes the aforementioned problems. Additionally, an apparatus and technique that can be readily implemented or retrofitted into existing hardware systems would provide a further cost benefit.